The present invention relates to a spin finish for synthetic fiber.
Upon emerging from a spinneret, many synthetic fibers require the application of a spin finish in order to further process the spun yarn. Because a spin finish may be present in a minimal layer on fiber, the spin finish acts as an interface between the fiber and the metallic surfaces such as guides and rollers which contact the fiber during such processing as drawing or relaxing.
The art teaches many spin finishes for conventional industrial, carpet, and textile yarn. For example, spin finishes comprising lubricants of polyalkylene glycols with molecular weights of 300 to 1,000 and a second component are taught by U.S. Pat. No. 4,351,738 (see Comparative Examples) and commonly assigned U.S. Pat. Nos. 3,940,544; 4,019,990; and 4,108,781. U.S. Pat. No. 4,340,382 teaches a finish comprising a nonionic surfactant of polyalkylene glycol block copolymer.
Spin finishes comprising lubricants of polyalkylene glycols with molecular weights of greater than 1,000 and other components such as esters, an anionic compound, or polyalkylene oxide modified polysiloxane are taught by U.S. Pat. Nos. 3,338,830; 4,351,738 and 5,552,671 and Research Disclosures 19432 (June 1980) and 19749 (September 1980). See also Kokai Patent Publication 15319 published Jan. 23, 1987. Unfortunately, spin finishes comprising polyalkylene glycols wherein the preferred or lowest molecular weight exemplified is xe2x89xa72,000 may form deposits on the metallic surfaces which they contact during manufacturing.
U.S. Pat. No. 5,507,989 teaches a spin finish wherein the boundary lubricant is a polyalkylene glycol having a molecular weight of xe2x89xa79,000.
U.S. Pat. No. 4,442,249 teaches a spin finish comprising an ethylene oxide/propylene oxide block copolymer with a molecular weight greater than 1,000; an alkyl ester or dialkyl ester or polyalkyl ester of tri- to hexaethylene glycol lubricant; and a neutralized fatty acid emulsifier. Unfortunately, spin finishes comprising these block copolymers also may form deposits on the metallic surfaces which they contact during manufacturing and these textile spin finish compositions may be inadequate for the more severe conditions used in industrial fiber production.
Commonly assigned U.S. Pat. Nos. 3,681,244; 3,781,202; 4,348,517; 4,351,738 (15 moles or less of polyoxyethylene); and 4,371,658 teach the use of polyoxyethylene castor oil in spin finishes.
Another spin finish composition for conventional industrial yarn is taught by commonly assigned U.S. Pat. No. 3,672,977 which exemplifies a spin finish comprising coconut oil, ethoxylated lauryl alcohol, sodium petroleum sulfonate, ethoxylated tallow amine, sulfonated succinic ester, and mineral oil. See also commonly assigned U.S. Pat. Nos. 3,681,244; 3,730,892; 3,850,658; and 4,210,710.
Over the years, processes for manufacturing industrial yarns have become more demanding. See for example the processes for making dimensionally stable polyester fiber taught by commonly assigned U.S. Pat. Nos. 5,132,067; 5,397,527; and 5,630,976. Further, a general trend exists in the yarn converting industry towards direct cabling machines to reduce conversion costs. Cost reductions are achieved in part, as direct cabling machines operate at considerably higher speeds (30-50% greater) and complete two steps at once compared to conventional ring twisters. However, the demands placed on the yarn finish to preserve yarn mechanical quality are much greater with direct cabling machines. Thus, a spin finish which enhances yarn processability and contributes to improved yarn performance is needed in the art.
We have developed a spin finish which responds to the foregoing need in the art. The present spin finish composition comprises at least about 10 percent by weight based on the spin finish composition of components (a) and (b) having the formula
R1xe2x80x94(CO)xxe2x80x94Oxe2x80x94(CH(R2)xe2x80x94CH2xe2x80x94O)yxe2x80x94(CO)zxe2x80x94R3 
wherein each of R1 and R3 is selected from the group consisting of hydrogen or an alkyl group having from one to 22 carbon atoms or an alkylene hydroxy group having from one to 22 carbon atoms,
x is zero or one,
R2 may vary within component (a) or component (b) and is selected from the group consisting of hydrogen or an alkyl group having from one to four carbon atoms,
y is zero, or from one to 25, and
z is zero or one,
in component (a), x and z are equal to zero and the average molecular weight of component (a) is less than or equal to 1,900 and if R2 varies, component (a) is a random copolymer; and
in component (b), at least x or z is equal to one or component (b) is a complex polyoxyethylene glyceride-containing compound having greater than 10 polyoxyethylene units;
up to five percent by weight based on the spin finish composition of component (c) of an alkoxylated silicone; and
at least about one percent by weight based on the spin finish composition of component (d) having the formula
R4(CH2O(CO)aR5)b 
wherein R4 is xe2x80x94Cxe2x80x94 or xe2x80x94COCxe2x80x94; a is 0 or 1; R5 is xe2x80x94H; from xe2x80x94CH3 to xe2x80x94C18H37; or xe2x80x94CH(R6)xe2x80x94CH2O; b is 4 or 6; and R6 is xe2x80x94H or xe2x80x94CH3 or xe2x80x94H and xe2x80x94CH3 in a ratio of 10:90 to 90:10.
The present invention is advantageous compared with conventional spin finishes applied to industrial yarn because the present spin finish enhances yarn processability as evidenced by low fuming, improved mechanical quality at lower amounts of spin finish per yarn, improved mechanical quality at higher draw ratios, and minimal depositing and improves yarn performance as evidenced by improved strength and wicking.
Other advantages of the present invention will be apparent from the following description and attached claims.